Conventionally, a combustion heater is used widely, in which a radiation member is heated by the combustion heat generated from the combustion of fuel gas, and industrial materials, food products or the like are heated by the radiation heat from a radiation surface of the radiation member. Regarding the combustion heater like this, for example, a technology is proposed in which materials or shapes having a high radiation factor are applied to the radiation surface in order to increase the radiation intensity (see Patent Document 1).
In the above combustion heater in the related art, fuel gas is combusted at a fuel gas outlet provided on the radiation surface, and exhaust gas is released into the surrounding environment without being gathered. Accordingly, since exhaust heat cannot be gathered, the thermal efficiency thereof may become low. In addition, since the area of the radiation surface becomes small due to the formation of the fuel gas outlet, it is difficult to increase the radiation intensity. Furthermore, there is a possibility that the temperature around the heater rises due to the heat of exhaust gas, or the surroundings are filled with exhaust gas, whereby the surrounding environment may not be improved.
Therefore, a combustion heater called a micro-combustor having improved thermal efficiency is proposed. In this combustion heater, the range over an inflow path for fuel gas, a combustion chamber, and an outflow path for the exhaust gas after combustion is formed into a sealed structure, the inflow path and the outflow path are disposed adjacent to each other, and the fuel gas before combustion is preheated by the heat of the exhaust gas, thereby improving the thermal efficiency (see Patent Document 2).